U.S. patent application number 13/182907 was filed with the patent office on 2012-01-26 for direct-current switch.
This patent application is currently assigned to Fuji Electric Co., Ltd.. Invention is credited to Toru Hosen, Hirofumi MATSUO, Kazuaki Mino, Hiroyuki Ota, Hironobu Shiroyama.
Application Number | 20120018404 13/182907 |
Document ID | / |
Family ID | 44816987 |
Filed Date | 2012-01-26 |
United States Patent
Application |
20120018404 |
Kind Code |
A1 |
MATSUO; Hirofumi ; et
al. |
January 26, 2012 |
DIRECT-CURRENT SWITCH
Abstract
A miniaturized direct-current switch with which power loss is
reduced when establishing continuity of a direct-current path is
provided. The direct-current switch includes an electronic
open/close switch inserted in a direct-current path along which a
direct current flows in order to make the direct-current path an
open circuit or a closed circuit, a parallel mechanical open/close
switch connected in parallel to the electronic open/close switch,
and a switch control circuit that controls the opening or closing
time difference mutually between the parallel mechanical open/close
switch and the electronic open/close switch, wherein the switch
control circuit makes the parallel mechanical open/close switch a
closed circuit a predetermined time after the electronic open/close
switch has been made a closed circuit.
Inventors: |
MATSUO; Hirofumi;
(Nagasaki-shi, JP) ; Mino; Kazuaki; (Tokyo,
JP) ; Ota; Hiroyuki; (Matumoto-shi, JP) ;
Hosen; Toru; (Matumoto-shi, JP) ; Shiroyama;
Hironobu; (Matumoto-shi, JP) |
Assignee: |
Fuji Electric Co., Ltd.
Kawasaki
JP
Hirofumi Matsuo
Nagasaki
JP
|
Family ID: |
44816987 |
Appl. No.: |
13/182907 |
Filed: |
July 14, 2011 |
Current U.S.
Class: |
218/8 |
Current CPC
Class: |
H01H 9/548 20130101;
H01H 33/596 20130101; H01H 9/542 20130101 |
Class at
Publication: |
218/8 |
International
Class: |
H01H 9/38 20060101
H01H009/38 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 23, 2010 |
JP |
2010-166553 |
Claims
1. A direct-current switch, comprising: an electronic open/close
switch inserted in a direct-current path along which a direct
current flows in order to make the direct-current path an open
circuit or a closed circuit; a parallel mechanical open/close
switch connected in parallel to the electronic open/close switch;
and a switch control circuit that controls the opening or closing
time difference mutually between the parallel mechanical open/close
switch and the electronic open/close switch, wherein the switch
control circuit makes the parallel mechanical open/close switch a
closed circuit after the electronic open/close switch has been made
a closed circuit, when making the direct-current path along which a
direct current flows a closed circuit.
2. The direct-current switch according to claim 1, wherein the
switch control circuit makes the parallel mechanical open/close
switch an open circuit when making the direct-current path along
which a direct current flows an open circuit, and makes the
electronic open/close switch an open circuit within a time longer
than the time needed for chattering, occurring due to the parallel
mechanical open/close switch being made an open circuit, to abate,
and shorter than the time taken for the temperature of the
electronic open/close switch to rise to a predetermined
temperature.
3. The direct-current switch according to claim 1, further
comprising: a serial mechanical open/close switch connected in
series to the electronic open/close switch, wherein the switch
control circuit, when making the direct-current path along which a
direct current flows a closed circuit, makes the electronic
open/close switch a closed circuit after a predetermined time
longer than the time needed for chattering, occurring due to the
serial mechanical open/close switch being made a closed circuit, to
abate.
4. The direct-current switch according to claim 1, further
comprising: a serial mechanical open/close switch connected in
series to the electronic open/close switch, wherein the switch
control circuit, when making the direct-current path along which a
direct current flows an open circuit, makes the serial mechanical
open/close switch an open circuit after making the electronic
open/close switch an open circuit.
5. The direct-current switch according to claim 1, further
comprising: a commutating diode connected to ends of both output
terminals so as to be reverse-biased.
6. The direct-current switch according to claim 3, comprising: a
regenerative diode connected in parallel to a series connection
circuit of the electronic open/close switch and serial mechanical
open/close switch so as to be reverse-biased.
7. A direct-current switch, comprising: an electronic open/close
switch to make a direct-current path along which a direct current
flows an open circuit or a closed circuit; a serial mechanical
open/close switch connected in series to the electronic open/close
switch; a switch control circuit that controls the opening or
closing time difference mutually between the serial mechanical
open/close switch and the electronic open/close switch; and a
commutating diode connected to ends of both output terminals so as
to be reverse-biased, wherein the switch control circuit makes the
electronic open/close switch a closed circuit after the serial
mechanical open/close switch has been made a closed circuit, when
making the direct-current path a closed circuit.
8. A direct-current switch, comprising: an electronic open/close
switch to make a direct-current path along which a direct current
flows an open circuit or a closed circuit; a serial mechanical
open/close switch connected in series to the electronic open/close
switch; a switch control circuit that controls the opening or
closing time difference mutually between the serial mechanical
open/close switch and the electronic open/close switch; and a
regenerative diode connected in parallel to a series connection
circuit of the electronic open/close switch and serial mechanical
open/close switch so as to be reverse-biased, wherein the switch
control circuit makes the electronic open/close switch a closed
circuit after the serial mechanical open/close switch has been made
a closed circuit, when making the direct-current path a closed
circuit.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based on and claims priority from the
prior Japanese patent Application No. 2010-166553 filed on Jul. 23,
2010, the entire contents of which are incorporated herein by
reference.
BACKGROUND
[0002] 1. Field
[0003] The present invention relates to a direct-current switch
suitable for making a direct-current path, along which a direct
current flows, an open circuit or a closed circuit.
[0004] 2. Description of the Related Art
[0005] To date, alternating-current power has been supplied to
general households from an alternating-current utility grid (a
commercial power supply) using a synchronous generator. Meanwhile,
in recent years, dispersed power sources using photovoltaic power
generation, wind power generation, fuel cell power generation, or
the like, have attracted attention, and have started to be used in
general households. It is often the case that power generated by
these dispersed power sources is direct-current power. A
direct-current power supply that supplies the aforementioned power
from a dispersed power source directly to a general household,
office, or the like, is becoming accepted by society.
[0006] When supplying direct-current power from a utility grid (a
direct-current power source) to a direct-current distribution
system (for example, to indoor wiring that carries direct-current
power), and using the power, it is necessary to interpose a
direct-current switch between the indoor wiring and an electrical
instrument (for example, a television receiver), and control
whether or not to supply power to the electrical instrument.
Herein, characteristics required of the direct-current switch (a
switch carrying out an establishment of continuity and a
shutting-off of direct-current power) differ greatly from
characteristics required of a heretofore known alternating-current
switch (a switch carrying out an establishment of continuity and a
shutting-off of alternating-current power). The heretofore known
alternating-current switch is standardized based on the turning on
and off of an electric light illuminated by alternating current. To
date, various miniature types have been widely used as the
aforementioned alternating-current switch. However, when using this
kind of miniature alternating-current switch in "a current path
along which a direct current flows" (hereafter referred to as a
direct-current path), the amount of current which can be shut off
is limited to an extremely small amount. The reason for this is
that, unlike with alternating current, there is no time at which
direct current becomes zero, meaning that an arc generated when the
mechanical contacts of the switch open continues to be generated
continuously and without stopping, and an arc current caused by
generation of the arc continues to flow. Then, on an arc being once
generated, the arc current continues to flow, and it may happen
that it is substantially not possible to put the mechanical
contacts into an opened condition (a condition in which the switch
is shut off). Also, it may happen that a burnout of the contacts
occurs due to the heat generated by the arc. Then, a switch that
can withstand the heat generated by the arc and enable the contacts
to be opened is extremely large. That is, the heretofore known
alternating-current switch is not suitable for use in an electrical
instrument (for example, a household electrical product) that
operates on direct-current power supplied from a direct-current
power source.
[0007] Therefore, a direct-current switch shown as the related art
in FIG. 14 has been proposed (refer to JP-A-2007-213842). The
direct-current switch shown in FIG. 14 is suitable for use in a
direct-current distribution system 110. A direct-current switch
120a has an input terminal A, an input terminal B, an output
terminal C, and an output terminal D. The direct-current switch
120a includes a mechanical open/close switch 116, an electronic
open/close switch 115, a switch control circuit 114 that controls
the opening or closing time difference mutually between the
mechanical open/close switch 116 and the electronic open/close
switch 115, and a control switch 117. Then, the mechanical
open/close switch 116 is opened after the electronic open/close
switch 115 inserted in series in a bus bar 13 has been opened. By
so doing, an arc is prevented from being generated in a condition
in which the mechanical open/close switch 116 is opened (the
current path is shut off), and it is possible to shut off (open)
the current path of direct-current power supplied to a load 130
with a miniature mechanical open/close switch 116.
[0008] In the direct-current switch 120a disclosed in
JP-A-2007-213842, continuity is established in both the mechanical
open/close switch 116 and the electronic open/close switch 115 when
establishing continuity (closing) of the direct-current path.
Herein, it may be that although the contact resistance of the
mechanical open/close switch 116 is in the region of, for example,
a few m.OMEGA. (milliohm), the contact resistance of the electronic
open/close switch 115 is in the region of, for example, a few
hundred m.OMEGA.. For this reason, when the aforementioned
direct-current switch establishes continuity (closing) of the
current path for a long time, resistance loss (power loss) in the
electronic open/close switch 115 cannot be ignored, and heat
generation due to the resistance loss cannot be ignored either.
[0009] Herein, in order to reduce the contact resistance of the
electronic open/close switch 115, a possible solution is to
increase the chip size of the electronic open/close switch 115,
which is formed from a semiconductor, and reduce the resistance
when continuity is established. Also, a possible solution is to
reduce the turn-on voltage when continuity is established.
Furthermore, with regard to heat generation occurring in the
electronic open/close switch 115, while it is not possible to
prevent the heat generation itself, it is possible to prevent a
rise in temperature of the electronic open/close switch 115 by
using a heat sink formed from a material with a high thermal
conductivity. However, when increasing the chip size, the cost of
the electronic open/close switch 115 increases. Also, when using a
heat sink, it is not possible to avoid an increase in size of the
direct-current switch.
SUMMARY
[0010] Additional aspects and/or advantages will be set forth in
part in the description which follows and, in part, will be
apparent from the description, or may be learned by practice of the
invention.
[0011] An object of embodiments of the invention is to provide a
miniaturized direct-current switch with which power loss is reduced
when establishing continuity (closing) of a direct-current
path.
[0012] In order to achieve the object, a direct-current switch of
one aspect of the invention includes an electronic open/close
switch inserted in the direct-current path along which a direct
current flows in order to make the direct-current path an open
circuit or a closed circuit, a parallel mechanical open/close
switch connected in parallel to the electronic open/close switch,
and a switch control circuit that controls the opening or closing
time difference mutually between the parallel mechanical open/close
switch and the electronic open/close switch, wherein the switch
control circuit makes the parallel mechanical open/close switch a
closed circuit a predetermined time after the electronic open/close
switch has been made a closed circuit.
[0013] According to embodiments of the invention, by including a
mechanical open/close switch, an electronic open/close switch and a
switch control circuit that controls the mechanical open/close
switch and the electronic open/close switch, it is possible to
provide a low-cost and miniaturized direct-current switch with
which power loss of the electronic open/close switch is reduced
when establishing continuity of (closing) a direct-current
path.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] These and/or other aspects and advantages will become
apparent and more readily appreciated from the following
description of the embodiments, taken in conjunction with the
accompanying drawings of which:
[0015] FIG. 1 is a diagram showing a first embodiment;
[0016] FIGS. 2A to 2C are diagrams showing the opening and closing
procedures of a parallel mechanical open/close switch and an
electronic open/close switch in the first embodiment in timing
charts;
[0017] FIG. 3 is a diagram showing a working example of a
direct-current switch shown in FIG. 1;
[0018] FIG. 4 is a diagram showing a second embodiment;
[0019] FIGS. 5A to 5D are diagrams showing the opening and closing
procedures of a parallel mechanical open/close switch, electronic
open/close switch, and serial mechanical open/close switch in the
second embodiment in timing charts;
[0020] FIG. 6 is a diagram showing a third embodiment;
[0021] FIG. 7 is a diagram showing a first modification example of
a direct-current switch;
[0022] FIG. 8 is a diagram showing a second modification example of
a direct-current switch;
[0023] FIG. 9 is a diagram showing a third modification example of
a direct-current switch;
[0024] FIG. 10 is a diagram showing a fourth modification example
of a direct-current switch;
[0025] FIG. 11 is a diagram showing a fifth modification example of
a direct-current switch;
[0026] FIG. 12 is a diagram showing a sixth modification example of
a direct-current switch;
[0027] FIG. 13 is a diagram showing a seventh modification example
of a direct-current switch; and
[0028] FIG. 14 is a diagram showing background art.
DESCRIPTION OF EMBODIMENTS
[0029] Hereafter, a description will be given of embodiments of the
invention.
[0030] A direct-current switch of a first embodiment includes an
electronic open/close switch inserted in a direct-current path
along which a direct current flows in order to make the
direct-current path an open circuit or a closed circuit, a parallel
mechanical open/close switch connected in parallel to the
electronic open/close switch, and a switch control circuit that
controls the opening or closing time difference mutually between
the parallel mechanical open/close switch and the electronic
open/close switch. Then, the switch control circuit makes the
parallel mechanical open/close switch a closed circuit a
predetermined time after the electronic open/close switch is made a
closed circuit.
[0031] A direct-current switch of a second embodiment includes an
electronic open/close switch inserted in a direct-current path
along which a direct current flows in order to make the
direct-current path an open circuit or a closed circuit, a parallel
mechanical open/close switch connected in parallel to the
electronic open/close switch, a serial mechanical open/close switch
connected in series to the electronic open/close switch and
parallel mechanical open/close switch, and a switch control circuit
that controls the opening or closing time difference mutually among
the three switches--the parallel mechanical open/close switch,
serial mechanical open/close switch, and the electronic open/close
switch. Then, when making the direct-current path along which a
direct current flows a closed circuit, the switch control circuit
makes the electronic open/close switch a closed circuit a
predetermined time after the serial mechanical open/close switch
has been made a closed circuit, and lastly makes the parallel
mechanical open/close switch a closed circuit. Also, when making
the direct-current path along which a direct current flows an open
circuit, the switch control circuit makes the electronic open/close
switch an open circuit a predetermined time after the parallel
mechanical open/close switch has been made an open circuit, and
lastly makes the serial mechanical open/close switch an open
circuit.
[0032] A direct-current switch of a third embodiment includes an
electronic open/close switch inserted in a direct-current path
along which a direct current flows in order to make the
direct-current path an open circuit or a closed circuit, a serial
mechanical open/close switch connected in series to the electronic
open/close switch, a parallel mechanical open/close switch
connected in parallel to a series connection circuit formed of the
electronic open/close switch and the serially connected mechanical
open/close switch, and a switch control circuit that controls the
opening or closing time difference mutually among the three
switches--the parallel mechanical open/close switch, serial
mechanical open/close switch, and the electronic open/close switch.
Then, when making the direct-current path along which a direct
current flows a closed circuit, the switch control circuit makes
the electronic open/close switch a closed circuit a predetermined
time after the serial mechanical open/close switch has been made a
closed circuit, and lastly makes the parallel mechanical open/close
switch a closed circuit. Also, when making the direct-current path
along which a direct current flows an open circuit, the switch
control circuit makes the electronic open/close switch an open
circuit a predetermined time after the parallel mechanical
open/close switch has been made an open circuit, and lastly makes
the serial mechanical open/close switch an open circuit.
[0033] A direct-current switch of a modification of the embodiments
(hereafter referred to as a modification example of the
embodiments) is such that a commutating diode or regenerative diode
is added to the direct-current switches of the first to third
embodiments, furthermore, to a direct-current switch having only an
electronic open/close switch and serial mechanical open/close
switch. The addition of a commutating diode solves the problem of
how to prevent the occurrence of a counter electromotive force
immediately after the direct-current switch is shut off. The
addition of a regenerative diode solves the problem of how to carry
out regeneration via the direct-current switch of power generated
in a motor, which is a load.
[0034] Hereafter, a detailed description will be given of the first
to third embodiments, and furthermore, of the modification of the
embodiments, but as the parallel mechanical open/close switch in
the first embodiment, and the parallel mechanical open/close switch
and serial mechanical open/close switch in the second and third
embodiments, are components of the direct-current switch, and these
are also components in the modification example of the embodiments,
a description of these mechanical open/close switches will be given
first.
[0035] The mechanical open/close switch has two contacts formed of
a conductive body, the mechanical open/close switch is inserted in
a direct-current path, which is a path along which a current flows,
and each contact of the mechanical open/close switch is connected
to one branch of the direct-current path, which is divided in two.
The configuration is such that the direct-current path is formed by
the two contacts coming into contact with each other and forming a
closed condition, and the direct-current path is shut off by the
two contacts separating from each other and forming an open
condition.
[0036] In the first embodiment and the second embodiment, as a
mechanical open/close switch 16, to be described hereafter, is
connected in parallel to an electronic open/close switch 15, to be
described hereafter, the mechanical open/close switch 16 is also
referred to as a parallel mechanical open/close switch 16,
clarifying the function thereof. Also, in the third embodiment, as
the mechanical open/close switch 16 is connected in parallel to the
electronic open/close switch 15, albeit via a mechanical open/close
switch 161, it is also referred to as the parallel mechanical
open/close switch 16 in the third embodiment.
[0037] In the second embodiment, as the mechanical open/close
switch 161, being connected in series to the parallel connection
circuit of the parallel mechanical open/close switch 16 and the
electronic open/close switch 15, is connected in series to at least
the electronic open/close switch 15, the mechanical open/close
switch 161 is also referred to as a serial mechanical open/close
switch 161, clarifying the function thereof. Also, in the third
embodiment, as the mechanical open/close switch 161 is connected in
series to the electronic open/close switch 15, the mechanical
open/close switch 161, in the same way, is also referred to as the
serial mechanical open/close switch 161, clarifying the function
thereof.
[0038] Also, in a direct-current switch of the fourth to seventh
modification examples wherein a regenerative circuit is added to
the direct-current switch, to be described hereafter, as a
mechanical open/close switch 116 functions as a serial mechanical
open/close switch, the mechanical open/close switch 116 is also
referred to as a serial mechanical open/close switch 116,
clarifying the function thereof.
[0039] Herein, "parallel" in a parallel mechanical open/close
switch means a connection aspect wherein the current is divided
into the electronic open/close switch disposed in the
direct-current path and the mechanical open/close switch (including
a case in which one branch of the divided current is zero). That
is, when the electronic open/close switch and mechanical open/close
switch are connected in parallel, the resistance value of the
electronic open/close switch is larger than the resistance value of
the mechanical open/close switch, meaning that a large portion of
the current flowing along the direct-current path flows through the
mechanical open/close switch. Also, when the electronic open/close
switch functions as an element having a constant turn-on voltage
(the voltage across the switch when there is continuity), rather
than functioning as a resistor, the current flows only through the
mechanical open/close switch, whose turn-on voltage is near
zero.
[0040] Also, "serial" in a serial mechanical open/close switch
means a kind of connection aspect wherein the current flowing
through the electronic open/close switch disposed in the
direct-current path flows through the mechanical open/close switch.
That is, when the electronic open/close switch and mechanical
open/close switch are connected in series, on one of them being
shut off (becoming open), no current flows through the portion of
the direct-current path in which the electronic open/close switch
and mechanical open/close switch are connected in series. With an
electrical instrument in which the installation of a mechanical
open/close switch is required by safety standards or the like, the
requirement can be met by using this kind of series connection.
First Embodiment
[0041] FIG. 1 is a diagram showing the first embodiment. A
description will be given, referring to FIG. 1, of a direct-current
switch 20a of the first embodiment. The direct-current switch 20a
is used inserted between a load 30 and a direct-current utility
grid (direct-current power source) 10. In FIG. 1, the
direct-current switch 20a is shown as a four terminal circuit
having an input terminal A1, an input terminal B1, an output
terminal C1, and an output terminal D1, but as the input terminal
A1 and the output terminal C1 are electrically the same place, the
same kind of working effect is also obtained when the
direct-current switch 20a is a three terminal circuit having the
input terminal A1, the input terminal B1, and the output terminal
D1, without providing the output terminal C1. The utility grid 10
is connected to the input terminal A1 (+ side) and the input
terminal B1 (- side). The load 30 is connected to the output
terminal C1 (+ side) and the output terminal D1 - side) of the four
terminal circuit and, although not shown, to the input terminal
(input-output terminal) A1 (+ side) and the output terminal D1 (-
side) when the direct-current switch 20a is a three terminal
circuit having the input terminal (input-output terminal) A1, the
input terminal B1, and the output terminal D1.
[0042] The direct-current switch 20a includes the parallel
mechanical open/close switch 16, the electronic open/close switch
15, a switch control circuit 14, and a control switch 17. Then, the
parallel mechanical open/close switch 16 and the electronic
open/close switch 15 are connected in parallel, and the parallel
connection circuit of the parallel mechanical open/close switch 16
and the electronic open/close switch 15 is inserted in the
direct-current path between the utility grid 10 and load 30.
[0043] The load 30 is an electrical instrument, for example, a
television receiver. The electrical instrument may be a rotary
instrument as well as a static instrument, and as the rotary
instrument, for example, a direct-current motor having a commutator
or inverter motor can be given as examples. The parallel mechanical
open/close switch 16 and the electronic open/close switch 15 of the
direct-current switch 20a are inserted in order to make the
direct-current path along which the direct current flows to the
load 30 an open circuit (a condition in which the direct-current
path is not formed) or a closed circuit (a condition in which the
direct-current path is formed).
[0044] That is, the parallel mechanical open/close switch 16 and
the electronic open/close switch 15 connected in parallel are such
that both the parallel mechanical open/close switch 16 and the
electronic open/close switch 15 are inserted in a minus side bus
bar 13 on the input terminal B1 side, and connected in series
between the utility grid 10 and load 30. For this reason, when
either one of the parallel mechanical open/close switch 16 or
electronic open/close switch 15 is closed (has continuity), the
direct-current path has continuity (is a closed circuit), and when
both the parallel mechanical open/close switch 16 and the
electronic open/close switch 15 are opened (shut off), the
direct-current path is shut off (an open circuit). With this
opening and closing action, it is possible to cut off the supply of
power to the load 30, or to supply power from the utility grid 10
to the load 30. In FIG. 1, the parallel mechanical open/close
switch 16 and the electronic open/close switch 15 are inserted in
the minus side bus bar 13, but the same working effect is also
achieved by inserting the parallel mechanical open/close switch 16
and the electronic open/close switch 15 in a plus side bus bar 12
on the input terminal A1 side.
[0045] The switch control circuit 14 controls the opening or
closing time difference mutually between the parallel mechanical
open/close switch 16 and the electronic open/close switch 15. At
this time, the control switch 17 carries out an opening or closing,
and provides the switch control circuit 14 with a trigger signal
which is the trigger for the opening or closing of the parallel
mechanical open/close switch 16 and the electronic open/close
switch 15. The control switch 17 is a switch operated by, for
example, a human.
[0046] FIGS. 2A to 2C are diagrams wherein the opening and closing
procedures of the control switch 17, parallel mechanical open/close
switch 16, and the electronic open/close switch 15 in the first
embodiment are shown in timing charts. FIG. 2A shows a shutting-off
(a shut-off condition) wherein the control switch 17 is open, and
continuity (a condition in which continuity is established) wherein
the control switch 17 is closed, FIG. 2B shows a shutting-off (a
shut-off condition) wherein the electronic open/close switch 15 is
open, and continuity (a condition in which continuity is
established) wherein the electronic open/close switch 15 is closed,
and FIG. 2C shows a shutting-off (a shut-off condition) wherein the
parallel mechanical open/close switch 16 is open, and continuity (a
condition in which continuity is established) wherein the parallel
mechanical open/close switch 16 is closed. The horizontal axis
shows a time t. Referring to FIGS. 2A to 2C, the opening and
closing actions of the control switch 17, electronic open/close
switch 15, and parallel mechanical open/close switch 16 will be
described. Firstly, a description will be given of the procedure
when the direct-current path is made a closed circuit by the
direct-current switch 20a.
[0047] The operator of the control switch 17 changes the control
switch 17 from being shut off to having continuity (refer to a time
t1 of FIG. 2A). The switch control circuit 14, based on the trigger
signal generated by the control switch 17, changes the parallel
mechanical open/close switch 16 and the electronic open/close
switch 15 from being shut off to having continuity (refer to a time
t1 of FIG. 2B, and a time t2 of FIG. 2C). That is, as shown in FIG.
2B, when the control switch 17 has continuity (is closed), the
electronic open/close switch 15 has continuity (is closed), in
principle with no delay in action, but with a very slight delay in
action in an actual semiconductor device. Meanwhile, as shown in
FIG. 2C, when the control switch 17 has continuity (is closed), the
parallel mechanical open/close switch 16 has continuity (is closed)
after a predetermined time .tau.1. Herein, during the predetermined
time .tau.1 between the time t1 and time t2, only the electronic
open/close switch 15 has continuity. Then, as power loss occurs in
the electronic open/close switch 15 during the predetermined time
.tau.1, the predetermined time .tau.1 is set to a short time in
order that the temperature of the electronic open/close switch 15
does not rise to or above a predetermined temperature (for example,
60.degree. C.).
[0048] It is sufficient that the predetermined time .tau.1 is equal
to or longer than the delay in action of the electronic open/close
switch 15. By increasing the length of the predetermined time
.tau.1, it is possible to ensure that the parallel mechanical
open/close switch 16 establishes continuity after the electronic
open/close switch 15 has established sufficient continuity (after
the turn-on voltage of the electronic open/close switch 15 has
become sufficiently low). By setting the predetermined time .tau.1
in this way, the circuit is closed with a high voltage still being
applied to the contacts of the parallel mechanical open/close
switch 16, as a result of which, it does not happen that thermal
loss occurs in the contacts.
[0049] That is, the maximum permissible length of the predetermined
time .tau.1 is determined according to the permissible temperature
of the electronic open/close switch 15, and the minimum permissible
length of the predetermined time .tau.1 is determined according to
the permissible thermal loss of the contacts of the parallel
mechanical open/close switch 16, and the speed with which the
electronic open/close switch 15 establishes continuity.
Furthermore, the longer is the predetermined time .tau.1, the
greater is the power loss occurring in the electronic open/close
switch 15 in the direct-current path. The predetermined time .tau.1
is determined taking the above into consideration.
[0050] In this way, it is ensured that the parallel mechanical
open/close switch 16 does not establish continuity before the
electronic open/close switch 15. When the parallel mechanical
open/close switch 16 establishes continuity before the electronic
open/close switch 15, there is a danger of an arc being generated
between the contacts of the parallel mechanical open/close switch
16, causing damage to the contacts. In particular, the possibility
of an arc being generated due to chattering of the contacts is
increased. Herein, chattering is a phenomenon wherein, when the
contacts of the parallel mechanical open/close switch 16 switch
over, the contacts alternate between making and breaking due to a
miniscule and extremely rapid mechanical vibration of the contacts,
causing continuity of the current flowing along the direct-current
path on and off, sustaining for the duration in the region of, for
example, 1 to 100 ms (milliseconds).
[0051] Next, a description will be given of the procedure when the
direct-current path is made an open circuit by the direct-current
switch 20a. The operator changes the control switch 17 from having
continuity to being shut off (refer to a time t3 of FIG. 2A). The
switch control circuit 14, based on the trigger signal generated by
the control switch 17, changes the parallel mechanical open/close
switch 16 from having continuity to being shut off (refer to a time
t3 of FIG. 2C). Also, the switch control circuit 14 changes the
electronic open/close switch 15 from having continuity to being
shut off at a time t4 a predetermined time .tau.2 after changing
the parallel mechanical open/close switch 16 from having continuity
to being shut off based on the trigger signal generated by the
control switch 17. Herein, the predetermined time .tau.2 between
the time t3 and time t4 is set to a time equal to or longer than
the time needed for the chattering of the parallel mechanical
open/close switch 16 to abate, and the predetermined time .tau.2 is
set within a time shorter than the time taken for the temperature
of the electronic open/close switch 15 to rise to a predetermined
temperature.
[0052] When changing from having continuity to being shut off with
the aforementioned procedure, the predetermined time .tau.2 is set
to a time longer than the time needed for the chattering of the
parallel mechanical open/close switch 16 to abate. Therefore, at a
point at which the parallel mechanical open/close switch 16 is
completely opened after the chattering of the parallel mechanical
open/close switch 16 has abated, the electronic open/close switch
15 is still closed. For this reason, when the electronic open/close
switch 15 is, for example, a MOSFET, the resistance value of the
electronic open/close switch 15 is low, and the voltage across the
electronic open/close switch 15 is small, for the duration of the
predetermined time .tau.2. Therefore, even in the event that a
chattering occurs between the contacts of the parallel mechanical
open/close switch 16 for a time within the predetermined time
.tau.2, no arc is generated between the contacts of the parallel
mechanical open/close switch 16.
[0053] Also, when the electronic open/close switch 15 is, for
example, a bipolar-transistor, it does not happen that a voltage
equal to or greater than the turn-on voltage of the electronic
open/close switch 15 is generated across the contacts. Therefore,
no arc is generated between the contacts of the parallel mechanical
open/close switch 16.
[0054] Also, as the predetermined time .tau.2 is set to a time
shorter than the time taken for the temperature of the electronic
open/close switch 15 to rise to the predetermined temperature (for
example, a temperature determined by safety standards, or a
temperature determined by a semiconductor rating), the electronic
open/close switch 15 maintains a safe, low temperature, and there
is no thermal breakdown occurring. Then, the direct-current path is
in a shut-off (open) condition at the point at which the electronic
open/close switch 15 is opened.
[0055] That is, the maximum permissible length of the predetermined
time .tau.2 is determined according to the permissible temperature
of the electronic open/close switch 15, and as the minimum
permissible length of the predetermined time .tau.2 is the time for
which the chattering of the parallel mechanical open/close switch
16 continues, the predetermined time .tau.2 is a time equal to or
longer than the time for which the chattering continues.
Furthermore, the longer is the predetermined time .tau.2, the
greater is the power loss occurring in the electronic open/close
switch 15 in the direct-current path. The predetermined time .tau.2
has been determined taking the above into consideration.
[0056] That is, in the first embodiment, the time for which the
electronic open/close switch 15 has continuity is determined in
such a way as to overlap the time for which the parallel mechanical
open/close switch 16 has continuity in an anterior direction (the
direction before t2) and a posterior direction--(the direction
after t3). Then, the predetermined time .tau.1, which is the time
overlapping in the anterior direction, and the predetermined time
.tau.2, which is the time overlapping in the posterior direction,
are set within a time shorter than the time taken for the
temperature of the electronic open/close switch 15 to rise to a
predetermined temperature, and are times such that it is possible
to ignore power loss occurring in the electronic open/close switch
15. Also, the predetermined time .tau.2 is set to a time equal to
or longer than the time needed for the chattering of the parallel
mechanical open/close switch 16 to abate.
[0057] FIG. 3 is a diagram showing a working example of the
direct-current switch 20a shown in FIG. 1. Referring to FIG. 3, a
description will be given of one example of a more specific
configuration of the direct-current switch 20a. A parallel
mechanical open/close switch 16a, which is one working example of
the parallel mechanical open/close switch 16, is configured having
a relay 50 that mechanically opens and closes contacts and a
bipolar-transistor 51 that drives the relay 50, and it is possible
to control a current flowing through a coil winding of the relay 50
via the bipolar-transistor 51. For example, the contacts are closed
when a current is flowing through the coil winding, and the
contacts are opened when no current is flowing through the coil
winding.
[0058] An electronic open/close switch 15a, which is one working
example of the electronic open/close switch 15, is formed with a
metal oxide semiconductor field effect transistor (MOSFET) 53 and a
bipolar-transistor 54 as main components. The connection point of a
resistor R1 and resistor R2, and the collector of the
bipolar-transistor 54, are connected to the gate of the MOSFET 53,
and the MOSFET 53 is configured in such a way as to open and close
a direct-current path. Herein, the configuration is such that the
gate voltage is lowered, and the drain-to-source resistance is
high, when making the electronic open/close switch 15a an open
circuit, and the gate voltage is raised, and the drain-to-source
resistance is low, when making the electronic open/close switch 15a
a closed circuit.
[0059] A switch control circuit 14a, which is one working example
of the switch control circuit 14, is configured of a digital logic
circuit 18 and a peripheral circuit. A resistor R4 is for supplying
an operating voltage to the digital logic circuit 18, and the
operating voltage is kept at a constant voltage by a Zener diode ZD
and a capacitor C. A resistor R3 is connected to one of the two
ends of a control switch 17, and a bus bar 13 is connected to the
other end of the control switch 17. A change between a shutting-off
and establishing of continuity of the control switch 17 is
transmitted as a trigger signal, and the trigger signal is input
into a signal input terminal I of the digital logic circuit 18. The
digital logic circuit 18 is equipped with a signal output terminal
O1 and a signal output terminal O2, and the configuration is such
that a signal from the signal output terminal O1 is applied to the
base of the bipolar-transistor 51, and a signal from the signal
output terminal O2 is applied to the base of the bipolar-transistor
54. With the aforementioned switch control circuit 14a, which is
one working example of the switch control circuit 14, it is
possible to realize the actions shown in the timing charts of FIGS.
2A to 2C. The configuration is such that the contacts of the relay
50 are closed when the level of the signal from the signal output
terminal O1 is high, and the drain-to-source resistance of the
MOSFET 53 is low when the level of the signal from the signal
output terminal O2 is low, that is, the electronic open/close
switch 15a is made a closed circuit.
[0060] In the heretofore described circuit example, a MOSFET is
used as the electronic open/close switch, and a bipolar-transistor
is used as a circuit portion that drives the MOSFET, but with
regard to the combination of the two, it is possible to obtain the
same benefit from any combination of semiconductor devices such as
a MOSFET, a bipolar-transistor, or an IGBT. For example, it is also
possible to use a bipolar-transistor as the electronic open/close
switch, and to use a MOSFET as a circuit portion that drives the
bipolar-transistor.
Second Embodiment
[0061] FIG. 4 is a diagram showing the second embodiment. FIG. 4
shows a direct-current switch 20b acting as a direct-current switch
of the second embodiment. The direct-current switch 20b of the
second embodiment includes a parallel mechanical open/close switch
16 and a serial mechanical open/close switch 161 inserted in a
direct-current path along which a direct current flows in order to
make the direct-current path an open circuit or a closed circuit,
an electronic open/close switch 15, and a switch control circuit
141. Herein, as the serial mechanical open/close switch 161 is
connected in series with the electronic open/close switch 15, it is
called a serial mechanical open/close switch, as heretofore
described.
[0062] A characteristic of the direct-current switch of the second
embodiment is that, while maintaining the characteristic of the
first embodiment wherein power loss in a closed circuit condition
of the direct-current path is small, furthermore, the serial
mechanical open/close switch 161 is inserted in series with the
electronic open/close switch 15 of the direct-current path, making
the shutting-off of the direct-current path more reliable, and
improving safety.
[0063] The parallel mechanical open/close switch 16 and serial
mechanical open/close switch 161 in the direct-current switch 20b
of the second embodiment have the same configuration as the
parallel mechanical open/close switch 16 in the direct-current
switch 20a of the first embodiment, and the electronic open/close
switch 15 in the direct-current switch 20b of the second embodiment
has the same configuration as the electronic open/close switch 15
in the direct-current switch 20a of the first embodiment.
[0064] Then, the parallel mechanical open/close switch 16 and the
electronic open/close switch 15 are connected in parallel, and this
parallel connection circuit and the serial mechanical open/close
switch 161 are connected in series. Therefore, a series connection
circuit, formed of the parallel connection circuit of the parallel
mechanical open/close switch 16 and the electronic open/close
switch 15, and the serial mechanical open/close switch 161
connected in series with the parallel connection circuit, is
disposed between a utility grid 10 and a load 30 so as to form a
series circuit therewith.
[0065] FIGS. 5A to 5D are diagrams wherein the opening and closing
procedures of a control switch 17, the parallel mechanical
open/close switch 16, the electronic open/close switch 15, and the
serial mechanical open/close switch 161 are shown in timing charts.
FIG. 5A shows a shutting-off (a shut-off condition) and continuity
(a condition in which continuity is established) of the control
switch 17, FIG. 5B shows a shutting-off (a shut-off condition) and
continuity (a condition in which continuity is established) of the
serial mechanical open/close switch 161, FIG. 5C shows a
shutting-off (a shut-off condition) and continuity (a condition in
which continuity is established) of the electronic open/close
switch 15, and FIG. 5D shows a shutting-off (a shut-off condition)
and continuity (a condition in which continuity is established) of
the parallel mechanical open/close switch 16. The horizontal axis
shows a time t. The above-mentioned control is carried out by the
switch control circuit 141.
[0066] Herein, the mutual relationship between the shutting-off (a
shut-off condition) and continuity (a condition in which continuity
is established) of the electronic open/close switch 15 and the
shutting-off (a shut-off condition) and continuity (a condition in
which continuity is established) of the parallel mechanical
open/close switch 16 indicated in FIGS. 5C and 5D is the same as
that indicated in FIGS. 2B and 2C. That is, the parallel mechanical
open/close switches 16 acts regarding the electronic open/close
switches 15 with the same temporal relationship shown in FIG. 5D
and FIG. 5C as shown in FIG. 2C and FIG. 2B.
[0067] That is, the parallel mechanical open/close switch 16
establishes continuity at a time t7, which is a predetermined time
.tau.4 after a time t6 at which the electronic open/close switch 15
has established continuity, and the predetermined time .tau.4
(refer to FIG. 5D) and the predetermined time .tau.1 (refer to FIG.
2C) are determined based on the same criterion. Also, although the
electronic open/close switch 15 is shut off at a time t9, which is
a predetermined time .tau.5 after a time t8 at which the parallel
mechanical open/close switch 16 has been shut off, the
predetermined time .tau.5 (refer to FIG. 5D) and the predetermined
time .tau.2 (refer to FIG. 2C) are determined based on the same
criterion.
[0068] Firstly, referring to FIGS. 5A to 5D, a description will be
given of the procedure when the direct-current path is made a
closed circuit by the direct-current switch 20b.
[0069] The operator of the control switch 17 changes the control
switch 17 from being shut off to having continuity (refer to a time
t5 of FIG. 5A). The switch control circuit 141 changes the serial
mechanical open/close switch 161 from being shut off to having
continuity (refer to a time t5 of FIG. 5B) based on a trigger
signal generated by the control switch 17. That is, as shown in
FIG. 5B, when the control switch 17 has continuity (closing), the
serial mechanical open/close switch 161 has continuity (closing).
Herein, even though the serial mechanical open/close switch 161 has
continuity, both the electronic open/close switch 15 and parallel
mechanical open/close switch 16 are opened, no current flows
through the serial mechanical open/close switch 161. Then, the
switch control circuit 141 establishes continuity in the electronic
open/close switch 15 a predetermined time .tau.3 after the time
t5.
[0070] The direct-current path is closed at a time t6 at which the
serial mechanical open/close switch 161 and the electronic
open/close switch 15 establish continuity, and power is supplied to
the load 30. Herein, the length of the predetermined time .tau.3
between the time t5 and time t6 is greater than that of the time
taken for the chattering of the contacts of the serial mechanical
open/close switch 161 to abate (die out). In this way, the
occurrence of an arc between the contacts of the serial mechanical
open/close switch 161 is prevented.
[0071] When changing from being shut off to having continuity with
the above-mentioned procedure, the electronic open/close switch 15
is still opened at the point at which the serial mechanical
open/close switch 161 is closed and, as no voltage is applied
across the contacts of the serial mechanical open/close switch 161,
no arc is generated between the contacts of the serial mechanical
open/close switch 161, even in the event that chattering
occurs.
[0072] Although the temporal relationship between the mutual
actions of the electronic open/close switch 15 and parallel
mechanical open/close switch 16 is the same as in the first
embodiment, as heretofore mentioned, a description will be given
below; the parallel mechanical open/close switch 16 establishes
continuity (closing) at the time t7 that is the predetermined time
.tau.4 after the time t6 at which the electronic open/close switch
15 has established continuity. Herein, it is desirable that the
predetermined time .tau.4 is a short time so that the temperature
of the electronic open/close switch 15 does not rise to or above a
predetermined temperature.
[0073] In the case there is absolutely no delay, a condition of
continuity is established immediately by a control signal from the
switch control circuit 141, in the action of the electronic
open/close switch 15, the predetermined time .tau.4 may be zero,
but by increasing the length of the predetermined time .tau.4, it
is possible to ensure that the parallel mechanical open/close
switch 16 establishes continuity after the electronic open/close
switch 15 has established sufficient continuity (after the turn-on
voltage of the electronic open/close switch 15 has become
sufficiently low). In the event that the parallel mechanical
open/close switch 16 were to establish continuity before the
electronic open/close switch 15, there is a possibility of an arc
being generated due to chattering of the contacts of the parallel
mechanical open/close switch 16, and this kind of control cannot be
employed.
[0074] Next, a description will be given of the procedure when the
direct-current path is made an open circuit by the direct-current
switch 20b. The operator changes the control switch 17 from having
continuity to being shut off (refer to a time t8 of FIG. 5A). The
switch control circuit 141 changes the parallel mechanical
open/close switch 16 from having continuity to being shut off
(refer to a time t8 of FIG. 5D) based on a trigger signal generated
by the control switch 17. Also, the switch control circuit 141
changes the electronic open/close switch 15 from having continuity
to being shut off at the time t9 that is the predetermined time
.tau.5 after changing the parallel mechanical open/close switch 16
from having continuity to being shut off based on the trigger
signal generated by the control switch 17. Herein, the
predetermined time .tau.5 is set to a time equal to or longer than
the time needed for the chattering of the parallel mechanical
open/close switch 16 to abate, and is set within a time shorter
than the time taken for the temperature of the electronic
open/close switch 15 to rise to a predetermined temperature.
Furthermore, the longer is the predetermined time .tau.5, the
greater is the power loss occurring in the electronic open/close
switch 15 in the direct-current path. The predetermined time .tau.5
is determined taking the above into consideration.
[0075] Then, the serial mechanical open/close switch 161 is made an
open circuit after a predetermined time .tau.6, which is after the
electronic open/close switch 15 has been made an open circuit.
Herein, the predetermined time .tau.6 may be zero, but by
increasing the length of the predetermined time .tau.6, it is
possible to ensure that the serial mechanical open/close switch 161
is shut off after the electronic open/close switch 15 is
sufficiently shut off.
[0076] When changing from having continuity to being shut off with
the aforementioned procedure, the electronic open/close switch 15
is still closed at a point at which the parallel mechanical
open/close switch 16 is opened and, even in the event that a
chattering occurs between the contacts of the parallel mechanical
open/close switch 16, it does not happen that a voltage equal to or
greater than the turn-on voltage of the electronic open/close
switch 15 is generated across the contacts of the parallel
mechanical open/close switch 16, and no arc is generated between
the contacts. Then, the direct-current path is put into a shut-off
(opened) condition at the point at which the electronic open/close
switch 15 is opened.
[0077] Then, lastly, the shutting-off of the direct-current path is
made more reliable by shutting-off (opening) the serial mechanical
open/close switch 161. The switch control circuit 141 controls in
such a way that the shutting-off of the serial mechanical
open/close switch 161 is carried out at a time t10 delayed by the
predetermined time .tau.6 after the time t9. It is desirable that
the length of the predetermined time .tau.6 is selected so that the
shutting-off of the serial mechanical open/close switch 161 is
carried out after the shutting-off (opening) of the electronic
open/close switch 15 has been sufficiently carried out (after the
electronic open/close switch 15 has been in a completely shut-off
condition). That is, in the case that the delay in the action of
the electronic open/close switch 15 is long, the predetermined time
.tau.6 is lengthened so that the contacts of the serial mechanical
open/close switch 161 are not damaged.
[0078] That is, in the second embodiment, the time for which the
electronic open/close switch has continuity is determined in such a
way as to overlap the time for which the parallel mechanical
open/close switch has continuity in the anterior and posterior
directions. Also, the time for which the serial mechanical
open/close switch has continuity is determined in such a way as to
overlap the time for which the electronic open/close switch has
continuity in the anterior and posterior directions. Herein, the
time needed for the chattering of the contacts of the serial
mechanical open/close switch to abate in such a way as to overlap
the time for which the electronic open/close switch has continuity
in the anterior direction.
Third Embodiment
[0079] FIG. 6 is a diagram showing the third embodiment. FIG. 6
shows a direct-current switch 20c acting as a direct-current switch
of the third embodiment. The direct-current switch 20c of the third
embodiment includes a parallel mechanical open/close switch 16 and
a serial mechanical open/close switch 161 inserted in a
direct-current path along which a direct current flows in order to
make the direct-current path an open circuit or a closed circuit,
an electronic open/close switch 15, and a switch control circuit
141. A characteristic of the direct-current switch of the third
embodiment is that, while maintaining the characteristic of the
first embodiment wherein power loss in a continuity condition of
the direct-current path is small, furthermore, the serial
mechanical open/close switch 161 is inserted in series in the
direct-current path, making the shutting-off of the direct-current
path more reliable, and improving safety.
[0080] The parallel mechanical open/close switch 16 and serial
mechanical open/close switch 161 in the direct-current switch 20c
of the third embodiment have the same configuration as the parallel
mechanical open/close switch 16 in the direct-current switch 20a of
the first embodiment, and the electronic open/close switch 15 in
the direct-current switch 20c of the third embodiment has the same
configuration as the electronic open/close switch 15 in the
direct-current switch 20a of the first embodiment.
[0081] Then, the series mechanical open/close switch 161 and the
electronic open/close switch 15 are connected in series, and this
series connection circuit and the parallel mechanical open/close
switch 16 are connected in parallel. Therefore, a parallel
connection circuit formed of the series connection circuit of the
series mechanical open/close switch 161 and the electronic
open/close switch 15 and the parallel mechanical open/close switch
16 connected in parallel to the series connection circuit is
disposed between a utility grid 10 and a load 30 so as to form a
series circuit therewith.
[0082] A comparison will be made of the second embodiment shown in
FIG. 4 and third embodiment shown in FIG. 6, focusing on the
connection aspect of the mechanical open/close switch and the
electronic open/close switch inserted in the bus bar 13. The serial
mechanical open/close switch 161 and the electronic open/close
switch 15 are connected in series in both the second embodiment
shown in FIG. 4 and the third embodiment shown in FIG. 6. Also, in
the second embodiment shown in FIG. 4, the parallel mechanical
open/close switch 16 is connected in parallel to the electronic
open/close switch 15, while in the third embodiment shown in FIG.
6, the parallel mechanical open/close switch 16 is connected in
parallel to the electronic open/close switch 15 via the serial
mechanical open/close switch 161.
[0083] Owing to the aforementioned commonality of connection aspect
of the direct-current switch 20b of the second embodiment and
direct-current switch 20c of the third embodiment, timing charts to
show the opening and closing procedures of a control switch 17, the
parallel mechanical open/close switch 16, electronic open/close
switch 15, and serial mechanical open/close switch 161 in the third
embodiment are the same as FIGS. 5A to 5D, so a description will be
given referring again to FIGS. 5A to 5D.
[0084] FIG. 5A shows a shutting-off (a shut-off condition) and
continuity (a condition in which continuity is established) of the
control switch 17, FIG. 5B shows a shutting-off (a shut-off
condition) and continuity (a condition in which continuity is
established) of the serial mechanical open/close switch 161, FIG.
5C shows a shutting-off (a shut-off condition) and continuity (a
condition in which continuity is established) of the electronic
open/close switch 15, and FIG. 5D shows a shutting-off (a shut-off
condition) and continuity (a condition in which continuity is
established) of the parallel mechanical open/close switch 16. The
horizontal axis shows time t. Such control is carried out by the
switch control circuit 141.
[0085] That is, although the parallel mechanical open/close switch
16 establishes continuity at a time t7 that is a predetermined time
.tau.4 after a time t6 at which the electronic open/close switch 15
has established continuity, the predetermined time .tau.4 (refer to
FIG. 5D) and the predetermined time .tau.1 (refer to FIG. 2C) are
determined based on the same criterion. Also, although the
electronic open/close switch 15 is shut off at a time t9, which is
a predetermined time .tau.5 after a time t8 at which the parallel
mechanical open/close switch has been shut off, the predetermined
time .tau.5 (refer to FIG. 5D) and the predetermined time .tau.2
(refer to FIG. 2C) are determined based on the same criterion.
Also, a predetermined time .tau.3 (refer to FIG. 5C) and a
predetermined time .tau.6 (refer to FIG. 5B) are times having the
same significance as in the second embodiment.
[0086] As the opening and closing procedure of the direct-current
switch 20c of the third embodiment is the same as that shown in the
second embodiment, a description will be omitted.
[0087] That is, in the third embodiment, the time for which the
electronic open/close switch 15 has continuity is determined in
such a way as to overlap the time for which the parallel mechanical
open/close switch 16 has continuity in the anterior and posterior
directions. Also, the time for which the serial mechanical
open/close switch 161 has continuity is determined in such a way as
to overlap the time for which the electronic open/close switch 15
has continuity in the anterior and posterior directions. Herein,
the time needed for the chattering of the contacts of the
mechanical open/close switch (the serial mechanical open/close
switch) to abate is such as to overlap the time for which the
electronic open/close switch has continuity in the anterior
direction.
[0088] In each of the heretofore described first to third
embodiments, a direct-current switch includes an electronic
open/close switch inserted in a direct-current path along which a
direct current flows in order to make the direct-current path an
open circuit or a closed circuit, a parallel mechanical open/close
switch connected in parallel to the electronic open/close switch,
and a switch control circuit that controls the opening or closing
time difference mutually between the parallel mechanical open/close
switch and the electronic open/close switch, and the switch control
circuit makes the parallel mechanical open/close switch a closed
circuit a predetermined time after the electronic open/close switch
has been made a closed circuit.
[0089] By configuring in this way, it does not happen that an arc
is generated between the contacts of the parallel mechanical
open/close switch due to chattering when the parallel mechanical
open/close switch is made a closed circuit. Also, as the parallel
mechanical open/close switch is made a closed circuit a
predetermined time after the electronic open/close switch has been
made a closed circuit, current flows through the electronic
open/close switch only for this predetermined time, and it is
possible to prevent a rise in temperature of the electronic
open/close switch. Then, a reduction in size of the parallel
mechanical open/close switch and the electronic open/close switch,
and furthermore, a reduction in size of a heat sink provided in the
electronic open/close switch, are achieved.
[0090] Also, the switch control circuit makes the parallel
mechanical open/close switch an open circuit when making the
direct-current path along which the direct current flows an open
circuit, and makes the electronic open/close switch an open circuit
within a time longer than the time needed for chattering occurring
due to the parallel mechanical open/close switch being made an open
circuit to abate, and shorter than the time taken for the
temperature of the electronic open/close switch to rise to a
predetermined temperature.
[0091] Also, in both the heretofore described second embodiment and
third embodiment, the direct-current switch includes a serial
mechanical open/close switch connected in series to the electronic
open/close switch, in addition to the electronic open/close switch
and parallel mechanical open/close switch, and when making the
direct-current path along which the direct current flows a closed
circuit, the electronic open/close switch is made a closed circuit
after a predetermined time longer than the time needed for
chattering occurring due to the serial mechanical open/close switch
being made a closed circuit to abate.
[0092] Also, when making the direct-current path, along which the
direct current flows, an open circuit, the serial mechanical
open/close switch is made an open circuit after the electronic
open/close switch has been made an open circuit.
[0093] By configuring in this way, as the parallel mechanical
open/close switch is made a closed circuit a predetermined time
after the electronic open/close switch has been made a closed
circuit in both the second embodiment and the third embodiment too,
in the same way as in the first embodiment, it does not happen that
an arc is generated between the contacts of the parallel mechanical
open/close switch due to chattering when the parallel mechanical
open/close switch is made a closed circuit. Also, current flows
through the electronic open/close switch only for this
predetermined time, and it is possible to prevent a rise in
temperature of the electronic open/close switch. Then, a reduction
in size of the parallel mechanical open/close switch and the
electronic open/close switch, and furthermore, a reduction in size
of a heat sink provided in the electronic open/close switch, are
achieved. In addition, as the serial mechanical open/close switch
and the electronic open/close switch are disposed in series in the
direct-current path, the two contacts of the serial mechanical
open/close switch are separated from each other by the serial
mechanical open/close switch being opened, the direct-current path
is physically shut off, and safety for a direct-current switch
further increases. Furthermore, as the serial mechanical open/close
switch is opened last, no arc is generated between the contacts of
the serial mechanical open/close switch.
Embodiment Modification Examples
Direct-Current Switch with Power Regenerative Circuit
[0094] In the first embodiment to the third embodiment, in the case
wiring from the output terminal C1 and the output terminal D1 of
the direct-current switch 20a to the load 30 is long, and the
wiring has inductance, in the case wiring from the output terminal
C2 and the output terminal D2 of the direct-current switch 20b to
the load 30 is long, and the wiring has inductance, or in the case
wiring from the output terminal C3 and the output terminal D3 of
the direct-current switch 20c to the load 30 is long, and the
wiring has inductance, giving special consideration to the
generation of the counter electromotive force in any of the load 30
side, bus bar side, or each direct-current switch (the
direct-current switch 20a, direct-current switch 20b, or
direct-current switch 20c) side is a problem to be solved from the
point of view of preventing a high voltage to the direct-current
switch from being applied. Also, in the case the load 30 is a load
such as a motor that has an inductance component, it is desirable
to give the same kind of consideration even when the wiring is
short. Furthermore, in the case the load is a motor, how to
effectively utilize the electromotive force generated is a problem
that needs to be solved.
[0095] That is, in the case an inductance load (a load having an
inductance component) is connected to the output side of each
direct-current switch, a large counter electromotive force is
applied between the output terminal C1 and the output terminal D1,
between the output terminal C2 and the output terminal D2, and
between the output terminal C3 and the output terminal D3,
immediately after the shutting-off of each direct-current switch.
Each direct-current switch and other instruments in the wire path
are affected by this counter electromotive force, and it may happen
that each direct-current switch and other instruments are
destroyed.
[0096] In order to prevent the aforementioned counter electromotive
force from being generated, it is desirable to provide a
commutating diode inside the load 30. It is possible to prevent a
large counter electromotive force from being generated due to the
working of the commutating diode. Whether or not a commutating
diode is provided inside the load 30 depends on the will of the
manufacturer of the electrical instrument which is the load,
meaning that it may happen that no commutating diode is provided
inside the electrical instrument. In this case, measures are taken
against the counter electromotive force in the wire path from the
direct-current switch as far as to the load, or inside the
direct-current switch.
[0097] Furthermore, when the load is a motor, it is more desirable
to provide a regenerative diode that returns electromotive force to
the utility grid side. The commutating diode itself and the
regenerative diode (power regenerative diode) itself are heretofore
known technologies. However, it is not yet known how to utilize the
commutating diode and regenerative diode technologies in a
direct-current switch in which the direct-current path between the
utility grid and the load is shut off by an electronic open/close
switch or mechanical open/close switch.
[0098] The following embodiments provide a direct-current switch
wherein a commutating diode and a regenerative diode are further
added to the heretofore described direct-current switch. Then, the
embodiments solve the problems of preventing the generation of the
counter electromotive force and returning the electromotive force
to the utility grid side.
[0099] As a measure against the counter electromotive force in each
direct-current switch, it is possible to provide in advance a
commutating diode between the output terminal C1 and the output
terminal D1, between the output terminal C2 and the output terminal
D2, and between the output terminal C3 and the output terminal D3,
inside each direct-current switch.
[0100] FIG. 7 is a diagram showing a first modification example of
a direct-current switch. In a direct-current switch 20d shown in
FIG. 7, a diode Df that functions as a commutating diode is
provided inside the direct-current switch. As each portion of the
direct-current switch 20d shown in FIG. 7 other than the diode Df
is the same as those of the direct-current switch 20a shown in FIG.
1, a description will be omitted. As it is sufficient to provide
the diode Df between the output terminal C1 and the output terminal
D1 so that it is reverse-biased, the position thereof is not
strictly specified. By providing the diode Df inside the
direct-current switch 20d so that it is reverse-biased in this way,
a forward current is caused to flow through the diode Df
immediately after the direct-current path of the load 30 having
inductance is opened, the generation of the counter electromotive
force is prevented, and it is possible to prevent the
direct-current switch 20d from being destroyed.
[0101] With regard to a regenerative diode, In the case that a
MOSFET is used as the electronic open/close switch in the
direct-current switch 20d, a body diode (refer to FIG. 3) which is
reverse-biased with respect to the MOSFET 35 performs as a
regenerative diode. Therefore, it is not absolutely necessary to
add a regenerative diode. In the case of using a bipolar-transistor
as the electronic open/close switch, a regenerative diode is
provided in the same position as the body diode. By so doing, a
regenerative current is caused to flow through the body diode which
is reverse-biased at a time of a normal action immediately after
the direct-current switch 20d is opened, and it is possible to
regenerate the power generated from the load 30 the utility
grid.
[0102] In FIG. 7, the diode Df is connected in parallel to an end
of both the output terminal C1 and the output terminal D1 of the
direct-current switch 20d so as to be reverse-biased, the reason
for this is to protect all the parts inside the direct-current
switch 20d. Although not shown, when the object is to particularly
protect the electronic open/close switch 15a (refer to FIG. 3), it
is more effective to provide the diode Df between the vicinity of
the electronic open/close switch 15a inserted in the bus bar 13 and
the bus bar 12 which is the other bus bar so that it is
reverse-biased.
[0103] FIG. 8 is a diagram showing a second modification example of
a direct-current switch. A direct-current switch 20e in FIG. 8 is
the direct-current switch 20b shown in FIG. 4 with a diode Df that
functions as a commutating diode and a diode Dr that functions as a
regenerative diode being connected thereto. The diode Dr is
connected between the input terminal B2 and the output terminal D2
so that it is reverse-biased. Also, the diode Df is connected
between the output terminal C2 and the output terminal D2 so that
it is reverse-biased.
[0104] By employing the aforementioned configuration, a forward
current is caused to flow through the diode Df immediately after
the direct-current path of the load 30 having inductance has been
opened, the generation of the counter electromotive force is
prevented, and it is possible to prevent the direct-current switch
20e from being destroyed. Also, by causing a forward current to
flow through the diode Dr, it is possible to regenerate the power
generated from the load 30 to the utility grid.
[0105] FIG. 9 is a diagram showing a third modification example of
a direct-current switch. A direct-current switch 20f in FIG. 9 is
the direct-current switch 20c shown in FIG. 6 with a diode Df that
functions as a commutating diode and a diode Dr that functions as a
regenerative diode being connected thereto. The diode Dr is
connected between the input terminal B3 and the output terminal D3
so that it is reverse-biased. Also, the diode Df is connected
between the output terminal C3 and the output terminal D3 so that
it is reverse-biased.
[0106] By employing the aforementioned configuration, a forward
current is caused to flow through the diode Df immediately after
the direct-current path of the load 30 having inductance has been
opened, the generation of the counter electromotive force is
prevented, and it is possible to prevent the direct-current switch
20f from being destroyed. Also, by causing a forward current to
flow through the diode Dr, it is possible to regenerate the power
generated from the load 30 to the utility grid.
[0107] FIG. 10 is a diagram showing a fourth modification example
of a direct-current switch. A direct-current switch 20g in FIG. 10
is the direct-current switch 120a shown in FIG. 14 with a diode Df
that functions as a commutating diode and a diode Dr that functions
as a regenerative diode being connected thereto. The diode Dr is
connected between an input terminal B and an output terminal D so
that it is reverse-biased. Also, the diode Df is connected between
an output terminal C and an output terminal D so that it is
reverse-biased.
[0108] In the direct-current switch 20g, a switch control circuit
114 makes an electronic open/close switch 115 a closed circuit
after a serial mechanical open/close switch 116 has been made a
closed circuit when making a direct-current path along which a
direct current flows a closed circuit, and makes the serial
mechanical open/close switch 116 an open circuit after the
electronic open/close switch 115 has been made an open circuit when
making the direct-current path along which a direct current flows
an open circuit. By so doing, it is possible to prevent an arc
discharge from occurring in the serial mechanical open/close switch
116.
[0109] By employing the aforementioned configuration, a forward
current is caused to flow through the diode Df immediately after
the direct-current path of a load 30 having inductance has been
opened, the generation of the counter electromotive force is
prevented, and it is possible to prevent the direct-current switch
20g from being destroyed. Also, by causing a forward current to
flow through the diode Dr, it is possible to regenerate the power
generated from the load 30 to the utility grid.
[0110] FIG. 11 is a diagram showing a fifth modification example of
a direct-current switch. A direct-current switch 20h in FIG. 11 is
the direct-current switch 20b shown in FIG. 4 with a diode Df that
functions as a commutating diode and a diode Dr that functions as a
regenerative diode being connected thereto. The diode Or is
connected in parallel to the serial mechanical open/close switch
161 so that it is reverse-biased. Also, the diode Df is connected
between the output terminal C2 and the output terminal D2 so that
it is reverse-biased.
[0111] By employing the aforementioned configuration, a forward
current is caused to flow through the diode Df immediately after
the direct-current path of the load 30 having inductance has been
opened, the generation of the counter electromotive force is
prevented, and it is possible to prevent the direct-current switch
20h from being destroyed. Also, by causing a forward current to
flow through the diode Dr and the body diode of the electronic
open/close switch 15, it is possible to regenerate the power
generated from the load 30 to the utility grid.
[0112] FIG. 12 is a diagram showing a sixth modification example of
a direct-current switch. A direct-current switch 20i in FIG. 12 is
the direct-current switch 20c shown in FIG. 6 with a diode Df that
functions as a commutating diode and a diode Dr that functions as a
regenerative diode being connected thereto. The diode Dr is
connected in parallel to the serial mechanical open/close switch
161 so that it is reverse-biased. Also, the diode Df is connected
between the output terminal C3 and the output terminal D3 so that
it is reverse-biased.
[0113] By employing the aforementioned configuration, a forward
current is caused to flow through the diode Df immediately after
the direct-current path of the load 30 having inductance has been
opened, the generation of the counter electromotive force is
prevented, and it is possible to prevent the direct-current switch
20i from being destroyed. Also, by causing a forward current to
flow through the diode Dr and the body diode of the electronic
open/close switch 15, it is possible to regenerate the power
generated from the load 30 to the utility grid.
[0114] FIG. 13 is a diagram showing a seventh modification example
of a direct-current switch. A direct-current switch 20j in FIG. 13
is the direct-current switch 120a shown in FIG. 14 with a diode Df
that functions as a commutating diode and a diode Dr that functions
as a regenerative diode being connected thereto. The diode Dr is
connected to the mechanical open/close switch (the serial
mechanical open/close switch) 116 so that it is reverse-biased.
Also, the diode Df is connected between the output terminal C and
the output terminal D so that it is reverse-biased.
[0115] As shown in the direct-current switch 20j, the switch
control circuit 114 makes the electronic open/close switch 115 a
closed circuit after the serial mechanical open/close switch 116
has been made a closed circuit when making the direct-current path
along which a direct current flows a closed circuit, and makes the
serial mechanical open/close switch 116 an open circuit after the
electronic open/close switch 115 has been made an open circuit when
making the direct-current path along which a direct current flows
an open circuit. By so doing, it is possible to prevent an arc
discharge from occurring in the serial mechanical open/close switch
116.
[0116] Also, by employing the heretofore described configuration, a
forward current is caused to flow through the diode Df immediately
after the direct-current path of the load 30 having inductance has
been opened, the generation of the counter electromotive force is
prevented, and it is possible to prevent the direct-current switch
20j from being destroyed. Also, by causing a forward current to
flow through the diode Dr and the body diode of the electronic
open/close switch 115, it is possible to regenerate the power
generated from the load 30 to the utility grid.
[0117] The heretofore described embodiment modification examples
include the diode Df (the commutating diode) connected to the two
output ends of the direct-current switch so that it is
reverse-biased. Furthermore, the modification examples include the
diode Dr (the regenerative diode) connected in parallel to the
electronic open/close switch so that it is reverse-biased, the
diode Dr (the regenerative diode) connected in parallel to the
series connection circuit of the electronic open/close switch and
serial mechanical open/close switch so that it is reverse-biased,
or the diode Dr (the regenerative diode) connected in parallel to
the mechanical open/close switch so that it is reverse-biased.
[0118] In the heretofore described embodiment modification
examples, a description has been given assuming that both the diode
Df that functions as a commutating diode and the diode Dr that
functions as a regenerative diode are provided. However, when the
load has an inductance component (for example, a wire inductance
component from either end of the commutating diode to the load, or
an inductance component of the load itself), it is possible to
prevent the generation of the counter electromotive force occurring
between the output terminals of the direct-current switch even when
providing only the commutating diode. Also, with the load being a
motor which generates electromotive force, it is possible to return
regenerative power to the utility grid, even when providing only
the regenerative diode.
[0119] When providing both the commutating diode and regenerative
diode, it is possible to prevent the generation of the counter
electromotive force occurring between the output terminals of the
direct-current switch and/or return regenerative power to the
utility grid with a still wider variety of loads when the load has
an inductance component, including when the load is a motor, as
heretofore described.
[0120] For example, when the load is a motor, the commutating diode
and regenerative diode act with a time difference, as described
below; immediately after the direct-current switch has been shut
off, the counter electromotive force caused by a wire inductance
component and the motor coil winding inductance component would be
generated, but it is possible to prevent the generation of the
counter electromotive force occurring with the commutating diode,
and the motor is rotated by a forward current flowing through the
commutating diode. Subsequently, when the forward current of the
commutating diode is dissipated, the motor becomes a generator, the
forward current flows through the regenerative diode, and it is
possible to return regenerative power to the utility grid.
Aspects of Various Uses of Direct-Current Switch
[0121] The direct-current switch of any of the heretofore described
embodiments can be used, configuring a plug inserted into an outlet
connected to a utility grid, a load, and the direct-current switch
as a unit, in the same way as a heretofore known switch built into
an electrical appliance. Also, the direct-current switch can also
be configured as an adaptor disposed as a separate device between a
utility grid and a load.
[0122] When using the direct-current switch as an adaptor, a plug
(not shown), the direct-current switch, and an outlet (not shown)
are configured as an integrated part. A plug for inserting into an
outlet provided in a utility grid is connected to an input terminal
(for example, an input terminal A1) and an input terminal (for
example, an input terminal B1), and an outlet of a form matching
the plug is connected to an output terminal (for example, an output
terminal C1) and an output terminal (for example, an output
terminal D1). Then, a heretofore known type of electrical
instrument is used as a load, the plug of the electrical instrument
is inserted into the outlet of the adaptor, and a switch provided
in the electrical instrument is in a normally closed condition. By
turning the direct-current switch disposed inside the adaptor on or
off (continuity/shut-off), it is possible to turn the heretofore
known type of electrical instrument on or off (continuity/shut-off)
safely and simply.
[0123] Herein, an electronic control is currently employed for most
electrical instruments that operate on a heretofore known
alternating-current system (for example, 100V single phase), and
the aforementioned electrical instruments also operates on a
direct-current system. Consequently, it is possible to operate the
aforementioned electrical instruments by connecting to a
direct-current system using an adaptor having a direct-current
switch.
[0124] With an electrical instrument supplied with power via the
aforementioned adaptor using a direct-current switch, it is
possible to turn the power supply on and off safely, and with no
arc being generated. Also, as it is possible to reduce the size of
the direct-current switch inside the aforementioned adaptor, it is
possible to reduce the size of the whole adaptor.
Modification Example of Direct-Current Switch Insertion Place
[0125] In the first embodiment to the third embodiment, and in the
embodiment modification examples having a commutating diode and
regenerative diode, a description has been given assuming that, in
every case, the mechanical open/close switch and the electronic
open/close switch are inserted between the input terminal B1 and
the output terminal D1, between the input terminal B2 and the
output terminal D2, between the input terminal B3 and the output
terminal D3, and between the input terminal B and the output
terminal D. However, it is also possible to achieve the desired
effect by inserting the mechanical open/close switch, the
electronic open/close switch, and the regenerative diode between
the input terminal A1 and the output terminal C1, between the input
terminal A2 and the output terminal C2, between the input terminal
A3 and the output terminal C3, and between the input terminal A and
the output terminal C. That is, it is possible to obtain the same
effect by inserting the serial mechanical open/close switch and/or
parallel mechanical open/close switch, the electronic open/close
switch, and the regenerative diode either on the bus bar 12 or the
bus bar 13 sides.
[0126] A new embodiment wherein individual technologies disclosed
in the various embodiments are combined can also be implemented.
Also, the invention is not limited to the range of the heretofore
described embodiments and embodiments in which they are
combined.
[0127] Although a few embodiments have been shown and described, it
would be appreciated by those skilled in the art that changes may
be made in these embodiments without departing from the principles
and spirit of the invention, the scope of which is defined in the
claims and their equivalents.
* * * * *